1. AAFS, American Academy of Forensic Sciences website: http://www.aafs.org/about-aafs (accessed 11.10.13).
2. ABFDE, American Board of Forensic Document Examiners website: http://www.abfde.org/ (accessed 11.10.13).
3. Ames on Forgery. The Boston Book Company;Ames;Boston,1901
4. Army, US Army Criminal Investigation Command website: http://www.cid.army.mil/ (accessed 11.10.13).
5. ASQDE, American Society of Questioned Document Examiners website: http://www.asqde.org/ (accessed 11.10.13).